PRIOR CONCURRENT THERAPY: Biologic therapy: No prior biologic therapy Chemotherapy: See Disease Characteristics At least 3 weeks since prior chemotherapy, including irinotecan, for metastatic or recurrent disease and recovered No other prior first-line chemotherapy agents for metastatic or recurrent disease No prior adjuvant irinotecan No prior oxaliplatin Endocrine therapy: Not specified Radiotherapy: At least 3 weeks since prior radiotherapy No prior radiotherapy to target lesions unless documented disease progression within the radiation portal Surgery: See Disease Characteristics More than 4 weeks since prior surgery for primary or metastatic disease and recovered Other: No prior investigational anticancer drug administered with irinotecan No other concurrent investigational drugs